An autonomous vehicle may be a vehicle that is capable of sensing its environment and navigating without human input. Navigating may include determining where to guide the vehicle in response to objects the autonomous vehicle detects.
In the United States, the National Highway Traffic Safety Administration (NHTSA) released a formal classification system in 2013 for automated vehicle classification. NHTSA automated vehicle classifications included: Level 0: The driver completely controls the vehicle at all times. Level 1: Individual vehicle controls are automated, such as electronic stability control or automatic braking. Level 2: At least two controls can be automated in unison, such as adaptive cruise control in combination with lane keeping. Level 3: The driver can fully cede control of all safety-critical functions in certain conditions. The car senses when conditions require the driver to retake control and provides a “sufficiently comfortable transition time” for the driver to do so. Level 4: The vehicle performs all safety-critical functions for the entire trip, with the driver not expected to control the vehicle at any time. As this vehicle would control all functions from start to stop, including all parking functions, it could include unoccupied cars. Under this classification system, an autonomous vehicle includes an automated vehicle in levels 2, 3 and/or 4.